This invention relates to an unwinding-mechanism releasing device for use in a camera. Hitherto, it has been a common practice for the device of the type described, upon unwinding of a film or the multiple exposure photography, to bring a clutch mechanism interposed between a winding mechanism and a sprocket into a disengaged condition by depressing an unwinding button, with the unwinding button being locked and hence retained in the position thus assumed. Many such unwinding devices of this type have been proposed, most of which utilize an automatic releasing means adapated to release an unwinding button from its locked condition. In most cases, however, a locking member is so designed as to be released at the end of the winding operation but before shutter release. This, however, offers shortcomings in that there sometimes arises a shifting or misalignment of an image plane on a film for example due to slightly premature release or, when the film reaches its end in the course of winding operation and is then stopped in the position at which the aforenoted locking member is released, there is a danger that the unwinding button will be impossible to lock for multiple exposure operation.